1. Field of the Invention
The present invention relates to an apparatus for providing heat to wafers and more particularly to an apparatus for rapid thermal precessing of wafers.
2. Description of Related Art
Heat treatment apparatuses are used in a variety of industries including the manufacture of semiconductor devices. These heat treatment apparatuses can be used for several different fabrication processes such as thermal annealing, thermal cleaning, thermal chemical vapor deposition, thermal oxidation and thermal nitridation. These treatments often require that the temperature of a wafer be elevated to as high as 350.degree. C.-1300.degree. C. before and during the treatment. Further, these treatments often require that one or more fluids be delivered to the wafer.
There are several design challenges to meeting the thermal requirements of heat treatment apparatuses. For instance, it is often desirable to quickly ramp up and/or ramp down the temperature of a wafer to be treated. During these rapid temperature changes the temperature uniformity of the wafer should be sufficient to prevent damage to the wafer. Wafers often cannot tolerate even small temperature differentials during high temperature processing. For instance, a temperature difference above 1.degree.-2.degree. C./cm at 1200.degree. C. can cause enough stress to produce slip in the silicon crystal of certain wafers. The resulting slip planes will destroy any devices through which they pass.
Delivery of fluid to the wafer can also present design challenges. For instance, the exposure of the wafer to the fluid should be uniform across the wafer to avoid uneven treatment results. Further, fluids within the heat treatment apparatus must often be rapidly evacuated from the heat treatment apparatus. Another challenge derived from fluid delivery is the replacement of fluids within the heating chamber with other fluids. This exchange of fluids must often occur with minimal interaction between the original and replacement fluids.